Investigating the reaction between Hydrochloric acid and marble chippings.

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Introduction

For my Chemistry Coursework I will be investigating the reaction between Hydrochloric acid and marble chippings. The marble that I will be testing will be from a gravestone at St Mary's Church, Ewell. The two factors that I will investigate will be concentration and pressure. I have chosen these because they will give me solid and reliable results. I have done some additional research to see what other factors affect the rate of reaction: Temperature: The higher the temperature the more energy the particles have causing more collisions. The more collisions there are the faster the reaction. Concentration: The higher the concentrations of hydrochloric acid the more particles there are affect the amount of collisions. There are more collisions increasing the rate of reaction. Surface Area: when there is a greater surface area of solid, collisions happen more frequently. The more collisions there are the faster the reaction. Catalyst: The catalyst increases the rate of reaction by creating more energy for the particles making them collide more with each other. As this research shows concentration is a good area to investigate. The reaction between hydrochloric acid and marble chippings is: CaCO3 + 2HCl CaCl2 + H2O + CO2 Collision Theory As the temperature rises, the average Speed of particles increases. At high temperatures, there are more collisions per second and this results in an increase in the rate of reaction. A reaction will only occur if the colliding particles possesses more than a certain minimum amount of energy. ...read more.

Middle

In addition I should wear an apron so that the acid can't touch my skin or clothes. Also I should tuck my tie in and that the rubber bung on the conical flask is securely on. Fairness To keep it a fair test, the variables need to be kept the same to prevent getting the wrong results. The temperature of the acid needs to be accurate to get the correct rates of the reacting marble chips. The size of the marble Chips needs to be kept the same because of them either having a larger or smaller surface area for the acid to react with. If it has a larger surface area than the previous chips the results would be wrong because it has a larger area to react with, therefore the time it would have taken would be more than should be. If it were compared to the smaller chips the time would be less because of it having a smaller surface area for the reaction to act on. The Hydrochloric acid cannot be used again after the reaction otherwise the acid will be less strong to act on the marble chips. Everything should be kept the same except the concentration of the hydrochloric acid and the marble chip. The marble chip will be 5 grams every experiment. Prediction My prediction is that if the concentration of the acid increases there will be an increase in the rate of reaction for example the highest concentration will have the fastest reaction time. ...read more.

Conclusion

As we look at the graph we can clearly see that in all results that as the molarity got higher the reaction speeded up. Before I did the experiments I predicted that the more concentrated the hydrochloric acid was the quicker the carbon dioxide would be produced. This was completely correct because what I thought would happen did. My apparatus was very sensitive and accurate especially the gas syringe, which is accurate to 1cm3. My results were reasonably reproducible in that most results were within 2cm3 of each other. My experiment was relatively easy to set up apart from keeping the temperature of the acid the same. At this point I am able to answer my main hypothesis which was how does changing the concentration of acid affect the rate of reaction between hydrochloric acid and calcium carbonate? The answer to this would be that by changing the concentration of the hydrochloric acid it will either make the rate of reaction slower or quicker and more or less gas would be produced depending on whether the concentrations were more or less. If I could do the experiment again I would have liked to have used exact cubes of marble chippings with the same surface area and weight. This would have made my experiment much more accurate. Appendix I have used a few books and resources to help me with my project: - My note book, GCSE Chemistry - Gallagher and Ingram text book, the Internet GCSE chemistry revision www.scool.co.uk Encyclopedia Britannica http:www.gsceworld.co.uk http://pc65.frontier.osrhe.edu http://www.scidiv.bcc ...read more.

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